the problem is the attribute iva ( I tried with Double, double, Float, float and mapping with SCALE and PRECISION.. nothing worked), WHEN this value is 0.0, the entity is NEVER loaded (retrieved) WITH Producto.

Im using Eclipselink 2.2.1]]>FiruzzZ Mising name2012-06-29T23:55:21-00:00Re: not retrieving entity when an attribute of it has value 0.0https://www.eclipse.org/forums/index.php/mv/msg/366660/893319/#msg_893319
By default, EclipseLink interprets '0' values as null for primary keys. This is configurable using the "eclipselink.id-validation" persistence property as described here:

Best Regards,
Chris]]>Chris Delahunt2012-07-03T14:26:27-00:00Re: not retrieving entity when an attribute of it has value 0.0https://www.eclipse.org/forums/index.php/mv/msg/366660/893321/#msg_893321
Please turn on logging to finest and try reading in the Iva entity directly using em.find for the entity with pk=3, and try using the refresh query hint on the query bringing in the Producto entity with the null reference. Is the Producto's fechaAlta also set?